The present invention relates to end-type seals and, primarily, to their sealing rings.
There are widely known end-type seals having a gland mounted in a casing and a sealing ring made from a graphite-containing material whose face surface bears against the gland.
This type of seal is used where a complete tightness or strictly limited leakage rates should be observed for a long period of service life. The leakages of liquid are comparatively high during the initial period of the seal operation, up to the moment when the cooperative surfaces of the gland and the sealing ring become run in so as to closely match each other. Here, accurately machining and matching these surfaces, making for reduced leakages, results in a more laborious process of making both the gland and the sealing ring. To overcome these disadvantages, a sealing ring with a tapered surface facing the gland has been proposed (Cf. U.S. Pat. No. 3,469,851 Cl. 277-85). This arrangement makes it possible to reduce to some extent the leakages of liquid during the initial period of the seal operation owing to a higher unit pressure in the contact area between the surfaces of the gland and the sealing ring.
It has also been proposed to make annular ridges on the surface of the sealing ring opposite to the surface thereof facing the gland. These ridges become deformed in the assembly of the seal under the pressure exerted on the sealing ring (Cf. U.S. Pat. No. 3,717,353, Cl. 277-96); thus, the inaccuracies of assembly are compensated for, this also resulting in somewhat reduced leakages during the initial period of operation of the seal. However, these leakages are relatively high in both cases.